code: def optimizer_step(self, epoch, batch_idx, optimizer, closure, **_):
      # pass self as a kwarg
      optimizer.step(closure, pl_module=self)
  
imports: import os
  import re
  from unittest import mock
  import pytest
  import torch
  from lightning.pytorch import Trainer
  from lightning.pytorch.demos.boring_classes import BoringModel
  from lightning.pytorch.plugins import MixedPrecision
  from torch import Tensor
  from tests_pytorch.helpers.runif import RunIf
label_desc: Use image node_id 6 for calling the TestPrecisionModel obj's underlying member method code with example usage: obj.optimizer_step(epoch, batch_idx, optimizer, closure) without return types